The present invention relates to a variable viscosity sprayable gel or gel foam cleaner composition and method for cleaning delicate and sensitive hydrophobic/super hydrophobic (hereon as “Hydrophobic”) surfaces such as optical lenses and electronic devices. More particularly, the present invention relates to a completely homogeneous sprayable gel or gel foam cleaner composition and method of cleaning wherein the gel clings to and dwells for extended time on an optical lens or electronic surface when applied thereon. Preferably, the sprayable gel cleaner composition hereof is packed in a spray bottle dispenser, aerosol or non-aerosol foam pump, squeezable tube or flexible pouch.
Sprayable low viscosity and water based liquid cleaning compositions such as glass cleaners, all-purpose cleaners, bathroom cleaners and polishing cleaners as well as optical lens cleaners are known and are used by many people. In general, these commercially available cleaning compositions have low viscosity, and consequently, have a tendency to overspray and drip or run off from the surface to which they are applied, such as vertical windows, bathroom mirrors or horizontal ceiling. Similarly, problems are observed with the hydrophobic optical lenses and electronic surfaces using the liquid lens cleaners. These water or liquid based cleaners may have ammonia and glycol ether solvents and typically bead up on the surface, have no clinging ability or dwelling time, and easily roll off from the surface onto a perimeter of the surface. Therefore, very little contact is made with the liquid cleaner and the surface to be cleaned. This drip or run off of the low viscosity cleaning composition leads to inefficient cleaning and waste of product as well as wetting of non-targeted areas on the articles, such as eyeglass frames and electronic device housings etc.
As illustrated in FIG. 1, a prior art liquid spray bottle dispenser A is shown dispensing a liquid B from a spray head C onto a surface D to be cleaned. FIG. 1 illustrates that a user has reduced control over the amount of liquid B delivered by the spray bottle dispenser A as it comes in contact with the surface such as an optical lens or an electronic device. Because the cleaner B is delivered to the surface D as a liquid, the liquid rolls off the surface flowing onto other fixtures of the article (such as an eyeglass frame E, a camera lens housing, a computer screen frame, a cell phone housing, etc.). The dispensed liquid may also collect to form a pool F on the optical surface and drips G or spills onto associate objects H such as a book, table, desk, floor, clothes, etc. Excess or uncontrolled spray can cause blemishing I or respiratory irritation to the user.
Generally, optical lenses such as eyeglasses, sun and sports lenses, safety glasses, camera lenses, telescope lenses, microscope lenses, and electronic surfaces such as touch screens, digital displays, computer monitors, tablet displays, telephone displays, and TV screens are made of hydrophobic surfaces such as plastic, hard coated plastic, polycarbonate plastic, high index plastic as well as glass. These surfaces can also be covered with an anti-reflective film together with a hydrophobic coating thereon. These additional films and coatings help to prevent reflection as well as unwanted wetting with water based cleaners or liquid and can also help make the surface easy to clean any finger prints, smudges and other contaminants thereon. These surfaces have prompted us to develop gel or gel foam based cleaners to prevent excess waste and runoff.
In recent years, the sprayable cleaning gel compositions have been reported by Faris in U.S. Pat. Nos. 5,705,470 and 5,977,050. Faris has disclosed substantially homogeneous and particle free sprayable cleaning gel compositions with viscosity ranging from 900 centipoises (cP) to about 5,500 cP at standard temperature and pressure. Faris discloses a composition of different glycol ethers and certain dispersants as necessary parts of the composition together with other components in it. Faris claims improved clinging and dwell time on the surface to be cleaned such as glass, metal, and painted surfaces. In addition, Faris also claims improved surface contact with his cleaning compositions during cleaning of highly hydrophilic surfaces such as glass and metals. Notably, hydrophilic surfaces are water attracting or retaining surfaces that act to retain moisture. Faris does not disclose anything about anti-reflective hydrophobic lens surfaces or electronic surfaces. Also, Faris could only achieve an upper end viscosity with his composition as 5,500 cP using recommended water soluble polymeric thickeners in high amount up to 10 percent. The high concentration of thickeners may affect the cleaning efficiency of the gel cleaner on hydrophobic optical and electronic surfaces.
Another sprayable cleaning gel composition is reported by Fligger, in Pat. App. No. US 2007/0117736 A1. Fligger discloses a sprayable high viscosity thixotropic surface cleaner composition that also has glycol ethers in it. The sprayable thixotropic cleaner taught by Fligger has viscosity in the range of 6,000 cP to 25,000 cP and has encapsulated suspended insoluble and abrasive particles in it. The composition is more targeted to clean hard surfaces such as glass and metals. In addition, the thixotropic gel cleaner of Fligger becomes semisolid on the surface after spraying. The solid particles in the thixotropic semisolid gel cleaner may abrade and damage the delicate hydrophobic optical lens or electronic surface to be cleaned. Therefore, the gel cleaner disclosed by Fligger may be inefficient and damaging if used to clean delicate surfaces.
Many other different types of sprayable cleaning gel compositions and methods are available on the market for different surfaces and purposes. However, a need still exists for a sprayable gel or gel foam cleaner composition and method of cleaning, which is completely homogeneous, has a wide range of viscosity at room temperature and pressure, has no suspended encapsulated particles or glycol ether solvents and which clings and dwells for extended time on the hydrophobic optical lens or the electronic device surface when sprayed or applied in a controlled fashion as gel or gel foam. There is also a need for a cleaning composition with an improved cleaning efficiency that does not cause damage to the surface.